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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Missed optimization in math expression: sin(x) / cos(x) => tan(x)"
href="https://bugs.llvm.org/show_bug.cgi?id=35596">35596</a>
</td>
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<th>Summary</th>
<td>Missed optimization in math expression: sin(x) / cos(x) => tan(x)
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>Linux
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Common Code Generator Code
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>zamazan4ik@tut.by
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>clang(trunk) with '--std=c++17 -O3 -march=native -ffast-math' flags for this
code:
#include <cmath>
double test(double a)
{
return sin(a) / cos(a);
}
generates this assembly:
test(double): # @test(double)
sub rsp, 24
lea rdi, [rsp + 16]
lea rsi, [rsp + 8]
call sincos
vmovsd xmm0, qword ptr [rsp + 16] # xmm0 = mem[0],zero
vdivsd xmm0, xmm0, qword ptr [rsp + 8]
add rsp, 24
ret
GCC (trunk) with '--std=c++17 -O3 -march=native -ffast-math' flags generates
more optimal code:
test(double):
jmp tan</pre>
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